I've tried using the classifiers in ArcMap which only supports one ancillary dataset and I tried using Orfeo in QGIS 2.18, though the Orfeo Image Classification tool does not accept any ancillary raster datasets. I can create a training model using multiple bands and images in Orfeo but Image Classification only accepts one raster file so I can't feed it the extra ancillary data I used during the training.
Besides the original satellite image, I want to add in NDVI, NDWI, and DEM's to help the classifier just so you guys have an idea of what I'm trying to do. I haven't come across something like this besides creating a completely custom classifier.
How do I Classify With Multiple Ancillary Datasets using QGIS?
EDIT: I've figured it out. I just make a new composite raster image which includes the ancillary data as additional bands or create a virtual raster catalog. This way I can use the new composite raster with classifiers in any Remote Sensing software which often accepts only 1 raster file at a time. I've already tested this with my low spectral resolution data and it helped my classification output by adding NDVI and a NDWI as extra bands.